link to this page (I have added the bolding) NOTE ADDED JULY 2005: This page describes a method by which the location of the MER rovers could have been determined, using data from the Mars Relay on Mars Global Surveyor. However, the approach was not needed because the rover team quickly determined where the rovers were located, and this was followed within days by acquisition of Mars Global Surveyor Mars Orbiter Camera images that actually showed the hardware on the surface. The reader of this section should understand that this information has been superseded by actual events
Here is a long article released on 24 January 2000 about finding the Pathfinder Lander and it says... This effort to photograph the Mars Pathfinder lander demonstrates that it is extremely difficult to find a lander on the surface of Mars using the Mars Orbiter Camera aboard the MGS spacecraft. This analysis suggests that it is not very likely that the December 1999 Polar Lander will be found by MOC.